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Defense in Depth

Layered Security Strategy

1. Physical Layer: Facilities, hardware protection
2. Perimeter Layer: Firewalls, intrusion prevention
3. Network Layer: Segmentation, monitoring
4. Host Layer: Endpoint protection, patch management
5. Application Layer: Secure coding, WAF
6. Data Layer: Encryption, access controls
7. User Layer: Training, behavior monitoring

Zero Trust Architecture

Core Principles

• Never Trust, Always Verify: Authenticate and authorize every request
• Assume Breach: Design for compromise scenarios
• Principle of Least Privilege: Minimal necessary access
• Microsegmentation: Granular network controls

Implementation Components

• Identity Verification: Multi-factor authentication (MFA)
• Device Security: Endpoint detection and response (EDR)
• Network Security: Software-defined perimeters
• Application Security: API security, secure coding
• Data Protection: Classification, encryption
• Analytics: User behavior analytics (UBA)

Access Control Models

Role-Based Access Control (RBAC)

• Structure: Users → Roles → Permissions
• Benefits: Simplified administration, consistent policies
• Challenges: Role explosion, rigid structure
• Best Practices: Regular role reviews, separation of duties

Attribute-Based Access Control (ABAC)

• Components:
  • Subject: User requesting access
  • Object: Resource being accessed
  • Action: Operation being performed
  • Environment: Context (time, location, device)
• Benefits: Fine-grained control, dynamic policies
• Challenges: Complex implementation, policy management

Mandatory Access Control (MAC)

• Characteristics: System-enforced security labels
• Use Cases: Government, military, high-security environments
• Examples: SELinux, classified information systems

Encryption and Cryptography

Symmetric Encryption

• Characteristics: Same key for encryption and decryption
• Algorithms:
  • AES (Advanced Encryption Standard): Industry standard
  • ChaCha20: Modern stream cipher
  • Legacy: 3DES (deprecated), Blowfish
• Use Cases: Bulk data encryption, disk encryption
• Key Management: Secure distribution and storage challenge

Asymmetric Encryption

• Characteristics: Public/private key pairs
• Algorithms:
  • RSA: Widely used, key sizes 2048+ bits
  • Elliptic Curve (ECC): Smaller keys, equivalent security
  • Post-Quantum: Preparing for quantum computing threats
• Use Cases: Key exchange, digital signatures, SSL/TLS

Hash Functions and Digital Signatures

• Secure Hash Algorithms:
  • SHA-2: SHA-256, SHA-512 (current standard)
  • SHA-3: Latest NIST standard
  • Avoid: MD5, SHA-1 (cryptographically broken)
• Digital Signatures: Non-repudiation, integrity verification
• Certificate Authorities: Public Key Infrastructure (PKI)

Modern Security Technologies

Artificial Intelligence and Machine Learning

• Applications:
  • Threat Detection: Anomaly detection, behavioral analysis
  • Incident Response: Automated analysis and containment
  • Vulnerability Assessment: Code analysis, configuration review
• Challenges:
  • False Positives: Balancing sensitivity and accuracy
  • Adversarial ML: Attacks against AI systems
  • Data Quality: Training on representative datasets

Extended Detection and Response (XDR)

• Evolution: EDR → MDR → XDR
• Capabilities: Unified threat detection across multiple vectors
• Components: Endpoint, network, email, cloud, identity
• Benefits: Correlated analysis, reduced alert fatigue

Security Orchestration, Automation, and Response (SOAR)

• Purpose: Automate routine security tasks
• Components: Playbooks, case management, threat intelligence
• Benefits: Faster response times, consistent procedures
• Implementation: Integration with existing security tools

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